PITUITARY DISORDERS

Question 1

What is the other name for the pituitary gland?

Answer 1

Hypophysis

Question 2

What is the name of the system of blood vessels connecting the hypothalamus and the pituitary gland?

Answer 2

Hypophyseal portal system

Question 3

What is the other term for the anterior pituitary?

Answer 3

Adenohypophysis

Question 4

Name the 7 hormones produced by the anterior pituitary

Answer 4

1. GH (growth hormone)
2. TSH (thyroid stimulating hormone)
3. LH (luteinizing hormone)
4. FSH (follicle stimulating hormone)
5. PRL (prolactin)
6. ACTH (adrenocorticotropic hormone)
7. MSH (melanocyte stimulating hormone)

Question 5

What is the other name for the posterior pituitary?

Answer 5

Neurohypophysis

Question 6

Name the 2 hormones secreted by the posterior pituitary

Answer 6

1. Oxytocin
2. ADH (antidiuretic hormone)

Question 7

Why is the pituitary especially sensitive to changes in perfusion during pregnancy?

Answer 7

During pregnancy the pituitary gland increases in size without an increase in blood supply

Question 8

What is the name of hypopituitarism secondary to an obstetric hemorrhage?

Answer 8

Sheehan syndrome

Question 9

Why does Sheehan syndrome result in failure to lactate?

Answer 9

Decreased prolactin secretion

Question 10

Why does Sheehan syndrome result in amenorrhea, infertility, and breast/vaginal atrophy?

Answer 10

Decreased LH and FSH secretion

Question 11

Why does Sheehan syndrome result in hypothyroidism?

Answer 11

Decreased TSH secretion

Question 12

Why does Sheehan syndrome result in low blood pressure and low blood sugar?

Answer 12

Decreased ACTH (adrenocorticotropic hormone) secretion > adrenal insufficiency > decreased glucocorticoids

Question 13

What is the name of inability to concentrate urine secondary to insufficient ADH (antidiuretic hormone)?

Answer 13

Diabetes insipidus

Question 14

What are 3 kinds of diabetes insipidus?

Answer 14

1. Central DI
2. Nephrogenic DI
3. Psychogenic DI

Question 15

Which type of DI is caused by a brain lesion interfering with ADH synthesis?

Answer 15

Central DI (vasopressin deficiency)

Question 16

Which type of DI is caused by kidney disease/toxicity?

Answer 16

Nephrogenic DI (vasopressin resistance)

Question 17

Which type of DI is caused by compulsive thirst, resulting in a decreased concentration of ADH due to dilution?

Answer 17

Psychogenic DI (primary polydipsia)

Question 18

Besides polyuria and polydipsia, what are 4 symptoms of DI?

Answer 18

1. Dehydration
2. Hypernatremia
3. Hydronephrosis
4. Bladder distension

Question 19

How does tracking intake/output help to determine the etiology for DI?

Answer 19

In central and nephrogenic DI, the urine output will remain the same even with a decrease of intake

Question 20

How would a trial of ADH/Pitressin help determine the etiology for DI?

Answer 20

In central DI the problem is not enough ADH so hormone replacement would be beneficial.

In nephrogenic DI the problem is the kidneys are resistant to ADH so hormone replacement would have no effect.

Question 21

How would MRI help to determine the etiology for DI?

Answer 21

A healthy posterior pituitary appears very bright on MRI. In central DI it does not appear this way.

Question 22

What is the term for a test using various stimulating agents to trigger release of GH from the anterior pituitary?

Answer 22

Pituitary stimulation test

Question 23

In Sheehan syndrome, how would the pituitary appear on MRI?

Answer 23

“Empty sella”: appears shrunken/flattened

Question 24

What kind of solution is used to correct dehydration in diabetes insipidus?

Answer 24

Hypotonic solution (causes pull of fluid out of vasculature and into cells)

Question 25

What is the main target organ of growth hormone?

Answer 25

Liver

Question 26

What are 2 functions of growth hormone?

Answer 26

1. Stimulates liver to produce insulin-like growth factor (IGF-1) 2. Increases lipolysis and glycogenolysis to make ATP

Question 27

What is the purpose of insulin-like growth factor (IGF-1)?

Answer 27

Anabolic functions such as cell growth/reproduction, protein synthesis

Question 28

What are 2 hypothalamic hormones that regulate the release of growth hormone?

Answer 28

1. GHRH (growth hormone releasing hormone) 2. Growth hormone inhibiting hormone (somatostatin)

Question 29

What is the cause for excessive production of growth hormone in hyperpituitarism?

Answer 29

Benign somatotropic tumour of the anterior pituitary

Question 30

What are 2 reasons growth hormone is considered diabetogenic?

Answer 30

1. It promotes glycogenolysis causing hyperglycemia 2. Hyperglycemia causes excess insulin release

Question 31

In diagnosis of hyperpituitarism, why are IGF-1 and GH levels tested after administration of oral glucose?

Answer 31

Growth hormone secretion should normally be suppressed by increased blood glucose through negative feedback

Question 32

What are 2 classes of drugs used to treat hyperpituitarism?

Answer 32

1. Growth hormone inhibiting hormone analogs 2. Growth hormone receptor antagonists

Question 33

What is the term for hypersecretion of growth hormone during childhood and adolescence?

Answer 33

Pituitary gigantism

Question 34

What are 2 diseases that individuals with pituitary gigantism have an increased risk for?

Answer 34

1. Cardiomegaly 2. Heart failure